This book is aimed at ambitious players and we assume that the reader has an advanced chess education, knowing all the basic tactical motives. Also we assume that he is able to calculate longer variations and is trained to do so for more than 10 minutes if necessary. Wait, do I really need 10 minutes for every puzzle? No, relax. All chapters start with easy puzzles but the level of difficulty increases and depending on your skills you will need sometimes more than 20 minutes, sometimes you probably won´t even find the solution. We included some brain crushers from whom we think that even grandmasters will have problems solving. But that should not pose a problem. In our opinion the journey is the reward. Sometimes looking at a position for a long time and then finding something new you couldn't spot in the beginning, might be even more beneficial. The harder you try, the more you will benefit. We experienced from working with the book at home, it takes a lot of discipline, but we are certain that with a regular practice your calculation skills will improve a lot. Another good method is to train with a partner of similar strength or in a group. We used examples from the book in our own training sessions and think it will be very useful for chess coaches who are in need of new material for their pupils.

If not stated otherwise directly at the diagram or in the chapter introduction, every puzzle has a single best move as the solution. This move usually leads anywhere between a small and a big advantage and is not necessarily clearly winning. There are also a few puzzles that are marked with (=). In these puzzles your task is to find the only continuation that holds the balance. You will also find some puzzles marked with a (*). We think these puzzles are very deep and rather complicated. If you want, you can test your calculating abilities and spend a lot of time on these very rich positions or you can see them as practical puzzles, where the first move is the most important one to find, but you can't be sure about the consequences completely.

Our idea how to use the book optimally is the following. Take your time for every puzzle. Set up a chessboard, put up the position and then solve it without too much time pressure. Writing down your ideas is probably a good idea, especially if you plan to solve multiple puzzles in a row. In a lot of these positions there are many interesting ideas to discover, so try not to rush through the puzzles. The book is roughly planned to contain one year of calculation training (There will be a new puzzle book at the start of next year!). This is of course not the only way to use the book and we are sure you'll enjoy reading it regardless of your training methods.

Georgios Souleidis (1972) is an International Master and has a Master Degree in Communication Science. Souleidis, of Greek descent, was born in Germany and lives in Hamburg. He works as a chess coach and journalist. He is a six-time Greek team champion and won several open tournaments.

Dirk Sebastian (1979)is an International Master and chess coach, born, raised and living in Hamburg, Germany. He has one GM-norm, scored in the highest German "Bundesliga", where he plays for his home team for over 15 years.